It is a very good question ... why didnt the smoke alarms go off in the galley area? Why didnt anyone hear them?

The biggest thing that I have learned ... be very careful with re-charging of Li-ion batteries. It is important to use a proper charger, and not a cheap knockoff. I read the accounts of several people who experienced battery failures in phones (re-charging). It is a violent event. So now i am much more careful where I charge my phone at night.